Abstract:Chitinase is a kind of glycosyl hydrolases (GH) which hydrolyzes the chitin and other polymers. Chitinase plays an important function in the plant growth and development, as well as in the resistant process to diverse stresses. However, the tissue expression patterns and responses to diverse stresses of chitinase genes in soybean are still unclear, which seriously limited its application in genetic improvement. In this study, the chitinase family genes were identified in the wild soybean (Glycine soja Sieb. and Zucc.) and cultivated soybean (Glycine max(L.)Merr.), and the expression patterns were also analyzed. The results showed that 62 and 55 chitinase genes were identified in the wild soybean and cultivated soybean, which located on 17 and 18 chromosomes, respectively. The phylogenetic tree analysis showed that the chitinase genes were divided into five categories, with Class III and Class V belonging to the GH18 subfamily, while Class I, Class II and Class IV belonging to the GH19 subfamily. Further analysis found many cis-acting elements in the promoter regions of chitinase genes responding to various plant hormones and stresses.Further gene expression analyses in cultivated soybean showed that the chitinase genes presented differential expressions in different tissues and under different stress conditions. Among these genes, Gm.01G142400 and Gm.13G346700 were strongly induced in the leaves of resistant variety after soybean mosaic virus inoculation, Gm.03G254300 and Gm.20G164600 were induced in soybean roots after low phosphorus treatment, and Gm.08G259200 and Gm.19G245400 were induced in soybean nodules under low phosphorus condition. Gene expression analysis in wild soybean showed that the chitinase genes presented differential expressions in different tissues and after salt stress, among which Gs.02G002604 and Gs.02G002940 were highly induced in the leaves of tolerant variety after salt treatment. These results provide important references for further utilizing the chitinase genes in soybean genetic improvement.